1. Field of the Invention
The present invention relates to an etching apparatus of a glass substrate, and more particularly, to an etching apparatus of a glass substrate using a heating unit.
2. Discussion of the Related Art
Recently, research of flat panel displays such as liquid crystal display (LCD), plasma panel display (PDP), electroluminescent display (ELD), vacuum fluorescent display (VFD), etc., is being performed and these displays are being used in various apparatus.
Among these displays, LCDs are most widely used in that they have good picture quality and low power consumption characteristics. They are being used as the display in portable televisions and notebook computers.
Portable televisions or notebook computers are obtaining the popularity due to their lightness in weight. A main component of technology development is to decrease their weight. To this end, there are specific efforts to decrease the weight of the LCD itself.
Various ways for decreasing the weight of the LCD have been tried. However, LCD structure and current technology limit the decrease of weight and size to the main elements of the LCD.
In the meanwhile, glass substrate, which is one of the most basic elements of the LCD, still has margin to decrease the weight of the LCD according to developments in processing technologies. Since the glass substrate occupies most of the total weight of the LCD, research for decreasing the weight of the glass substrate is being performed for the purpose of decreasing the weight of the LCD.
In order to decrease the weight of the glass substrate, its thickness should be decreased preferentially. However, if the thickness decreases below a specific value, the glass substrate is broken during its processing or cracks are generated. Therefore, there is a limitation in decreasing the thickness of the glass substrate.
As a way for decreasing the thickness of the glass substrate, after an LCD is fabricated using a glass substrate having the specific thickness and more, the glass substrate is etched by dipping the glass substrate in an etching bath in which an etchant is contained.
This method, however, has disadvantages in that the glass substrate is nonuniformly etched due to the incompleteness of the glass substrate itself, or foreign particles generated during the etch process are again attached to the etched surface of the glass substrate and thus the surface of the glass substrate becomes irregular.
Hereinafter, a conventional etching apparatus is described with reference to the accompanying drawings.
FIG. 1 is a block diagram of a conventional etching apparatus of glass substrates.
First, a method for fabricating an LCD using a glass substrate is described.
A pair of large-sized glass substrates each having plural pixel regions are prepared. An LCD panel is fabricated using the pair of glass substrates by attaching the glass substrates with a space between the glass substrates. The LCD panel is cut to have a selected size. Liquid crystal is injected into the space between the glass substrates.
Specifically, in the LCD panel, on one glass substrate, generally called “TFT substrate”, gate lines and data lines normal to the gate lines are formed to thereby define pixel regions. A pixel electrode is formed on the defined unit pixel region. On the other glass substrate, generally called “color filter substrate”, color filter of red, green, blue (R, G, B) and a common electrode are arranged. The TFT substrate and the color filter substrate are aligned with a space for the liquid crystal between them and then they are attached each other. The attached substrates are cut and then the liquid crystal is injected into the space.
In the aforementioned LCD panel fabrication process, the attached substrates are etched to decrease the weight of the substrates prior to cutting the attached substrates.
Referring to FIG. 1, the conventional etching apparatus includes: an etching bath 1 for etching a glass substrate using an etchant to a selected thickness; a cleaning bath 6 for cleaning the etched substrate using deionized (DI) water; a drying bath 7 for drying the cleaned substrate; an etchant recycling part 2 for reproducing the etchant used in the etching bath 1; a DI supply part 3 for supplying DI water or distilled water; an undiluted etchant supply part 4 for supplying a undiluted etchant; and an etchant for mixing the DI and the undiluted etchant supplied from the DI supply part 3 and the undiluted etchant supply part 4 respectively with the recycled etchant supplied from the etchant recycling part 2 and supplying the mixed etchant to the etching bath 1.
FIG. 2 shows a detailed constitution of the etching bath 1 described in FIG. 1.
Referring to FIG. 2, the etching bath 1 includes: a container 1a containing the etchant; a bubble plate 1c established at a lower portion of the container 1a, for uniformly distributing a bubble using a gas supplied from an outside source; a gas supply tube 1b for supplying nitrogen (N2) or oxygen (O2) to the bubble plate 1c; and a container cover 1d for covering the upper portion of the container.
Here, generating the bubbles using nitrogen or oxygen gas is to uniformly etch the surface of the glass substrate by removing a reactant remaining on the surface of the etched glass substrate when the glass substrate is etched by an exothermic reaction with the etchant used.
The etchant mixing part 5 is connected to the etching bath 1 to supply the mixed etchant to the etching bath 1. The DI supply part 3 and the undiluted etchant supply part 4 are respectively connected to the etchant mixing part 5 to supply the DI water and the undiluted etchant to the etchant mixing part 5.
The etchant mixing part 5 has to mix the DI water and the undiluted etchant with the refined etchant in a constant concentration. To do so, a concentration measuring part 5a is provided in the etchant mixing part 5. The concentration measuring part 5a measures the concentration of the etchant mixed in the etchant mixing part 5. When the concentration of a finally mixed etchant in the etchant mixing part 5 arrives at a reference concentration, the concentration measuring part 5a informs a control part (not shown) of such a fact. By the control of the control part, the supply from the DI supply part 3 and the undiluted etchant supply part 4 is stopped.
The glass substrate is etched in the etch container 1a of the etching bath 1 by an exothermic reaction between the glass substrate and the finally mixed etchant supplied from the etchant mixing part 5.
The aforementioned conventional etching apparatus, however, has a drawback as follows.
As described above, since the glass substrate is etched in the etch container 1a of the etching bath 1 by an exothermic reaction between the glass substrate and the finally mixed etchant, and the etchant mixing part 5 supplies the finally mixed etchant to the etching bath 1 at a room temperature, a long etch time is required.